Strange behavior of my Epson C70

[Alberto]

I have just resolved a multi-head clog of my Epson C70.
Now all three colors, CMY, work ok. The problem is Black.
What happens is really strange. If I print telling the printer
driver that I am using Plain Paper, or Bright White Ink Jet Paper
or Photo Quality Ink Jet Paper, no black ink is spitted out the
nozzles... if I set the paper type as Premium Glossy Photo Paper
then black automagically appears on the print...

I suspect something related to the droplet size which probably
changes with the setting of paper type.
Can anybody be of help ? Thanks

Alberto

 

[Guest]

Because it is making a composite black mixing your colors. I think you
still have a problem with your black ink or nozzles.

 

[Alberto]

Because it is making a composite black mixing your colors. I think you
still have a problem with your black ink or nozzles.

Yes, I discovered that you are correct. It looks like, when printing
on Premium Glossy Photo Paper, the driver doesn't use the black ink to
render the black color, but a mix of the three primary CMY. Probably
they determined that this gives the best results.

BUT !!!

I found the cause of what I thought was a clogging of the nozzles...
not so... many and many and many cleaning cycles did nothing...
the culprit was just a small air bubble in the cartridge!
Tired of ink consuming and useless cleaning cycles, at last I tried,
with success, the following:
- I told the driver that wanted to replace the cartridges.
- When the carriage was moved at the cartridge replacing point,
I took out the black cartridge, which was the one that did not print,
shaked it four or five times, then replaced it.

At this point the printer started merrily to print with the black
ink, without banding or other problems. The only explanation can be
an air bubble that blocked the normal flow of ink in the cartridge.

All is well what ends well...

Alberto